This invention relates to headgear, and more particularly to a shock attenuation system for protective headgear.
This invention involves an improvement in shock attenuation systems for protective headgear of the type, such as shown for example in U.S. Pat. Nos. 3,292,180, 3,462,763, 3,600,714, 3,609,764, 3,668,704, and 3,887,076, comprising a deformable liner secured to the internal surface of an outer protective shell of the headgear, the liner deforming under an impact load applied to the shell for attenuating the shock upon the wearer. While the liners of prior systems initially provide adequate shock attenuation, they lose a substantial part of their shock attenuation properties with each impact, with the result that after a relatively small number of impact loadings of relatively high magnitude, they no longer provide adequate shock attenuation. The loss of shock attenuation properties is not, however, accompanied by any visible changes in the liners of prior systems, and a user cannot determine by visual inspection whether a particular piece of headgear which has been previously used still provides adequate protection.